Senior Software Engineer, Product

ABOUT ARENA INTELLIGENCE Arena is the platform for evaluating how AI models perform in the real world. Founded by researchers from UC Berkeley's SkyLab, we're on a mission to measure and advance the frontier of AI for real-world use, and to build the foundation for everyone to understand, shape, and benefit from it. Tens of millions of people use Arena each month to evaluate how frontier systems handle the work they actually do. The preferences they share power the most transparent, rigorous, and human-centered evaluations in AI. Leading AI labs, enterprises, and independent researchers rely on our work and open datasets to understand how models behave in real workflows: agentic coding, creative generation, professional productivity, and beyond. We go beyond leaderboards and decompose what human experience reveals about AI, so models advance toward the work people actually do. We're a team of researchers, academics, builders, and creatives from UC Berkeley, Google, Stanford, and DeepMind. We seek truth, move fast, and value craftsmanship, curiosity, and impact over hierarchy. We're building a company where thoughtful, curious people from all backgrounds can do their best work together, in an office culture that radiates excellence, energy, and focus. ABOUT THE ROLE We're looking for a Senior Software Engineer to own features end-to-end across Arena's platform — from understanding the problem, through designing and building the solution, to shipping it, measuring its impact, and iterating. This is a hands-on IC role for someone who writes code every day, cares deeply about what happens after launch, and is excited to shape how people interact with cutting-edge AI. YOU’LL - Own features from technical scoping through deployment and post-launch iteration — not just build them, but make sure they work - Design and extend schemas, APIs, and business logic to support new product capabilities - Ship high-quality product code across the stack - Incorporate real user feedback — from data, direct user contact, or your own product instincts — to improve what you've shipped - Work closely with ML researchers to turn research services to production, making them consumable for product development - Collaborate across design, product, and engineering to figure out what to build, not just how - Identify and advocate for improvements to development, testing, and deployment practices YOU’LL HAVE - 4+ years of experience in software engineering, with a focus on product development - Experience building user-facing web applications spanning frontend, backend/API, and database — in any stack. You understand the request lifecycle across layers - Clear, concise communication — you explain technical decisions well, distinguish your work from the team's, and proactively share context - Evidence of shipping and iterating — you can describe the full arc of a feature you owned: problem, solution, code, what happened after launch, and what you'd change now - A product engineering identity — you care about whether the thing you built actually worked for users, not just whether the code was clean - Genuine curiosity about AI evaluation and Arena's mission — you've looked at the product and can articulate why this domain matters to you BONUS EXPERIENCE - Familiarity with our stack: NextJS, React, TypeScript, Tailwind, ShadCN, HonoJS, Postgres, Vitest - Experience with Supabase or Vercel's AI SDK - You've shipped without PM or design support — determined what to build by talking to users or looking at data OUR TECH STACK: - NextJS - React + TypeScript - Tailwind + ShadCN - HonoJS - Postgres - Vitest WHAT WE OFFER - We offer competitive compensation and equity aligned to the markets where our team members are based. The base salary range will depend on the candidate’s permanent work location. - Comprehensive health and wellness benefits, including medical, dental, vision, and additional support programs. - The opportunity to work on cutting-edge AI with a smal